This conference will consider the pervasive role of viruses and the immune system and their interactions in the pathogenesis of neurodegenerative diseases. Such diseases are increasingly in evidence due to aging of the general population and the onslaught of AIDS and its associated encephalopathy. The five sessions will consider 1. The unique properties of the CNS that make it especially vulnerable to degenerative diseases; 2. The role of these vulnerabilities in the pathogenesis of neurodegenerative diseases with proven viral components; 3. The growing evidence for extensive immune interactions with the nervous system; 4. The implications of a larger CNS involvement by the immune system in neurodegenerative disease; 5. A consideration of neurodegenerative diseases of unknown etiology in the context of the preceding sessions. The conference will be held April 26-29, 1990, in North Carolina and will accommodate 125 participants. The objective is to bring together experts from neurobiology, virology and immunology who ordinarily have few opportunities to interact, to consider the problem of neurodegenerative disease from a multidisciplinary point of view. It is hoped that by sharing their unique perspectives, new insights will develop leading to new research opportunities. A fuller understanding of the neurodegenerative process is essential to the ultimate goal of effective intervention. A significant component of this meeting will be devoted to the pathogenesis of AIDS encephalopathy.